When to plant watermelons in Indianapolis: 16 May – 28 July

In Indianapolis, watermelon: sow for seedlings from 28 March to 30 June; plant into a greenhouse from 25 April to 28 July; plant out into open ground from 16 May to 28 July.

Watermelon in Indianapolis: soil, season and weather

In Indianapolis the soil, not frost, sets the date: the last frost is over around 14 April, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 16 May, 32 days later.

Last spring frost	14 April
Top 7 cm of soil at 18 °C	16 May, 32 days after the last frost
Into an unheated greenhouse	25 April – 28 July; April outside: 6.2 °C at night, 17.4 °C by day; card 18–35 °C
First autumn frost	6 November, 174 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	14 July – 25 September
Days left for picking	115
Daylight	13:21 on 18 April, 14:23 on 16 May
Watering outdoors when fruiting (card)	every 5 days; the driest month, November, has 9 rainy days

The same dates in Indianapolis hold for Cucumber, Bell Pepper, Eggplant, Zucchini and Pumpkin.

Watermelon in Indianapolis: care after planting

Planted on 16 May: in the first weeks water every 5 days.

Feeding, by the card’s schedule from that day:

16 May — feed: balanced (NPK)

Pests and diseases of watermelon to watch for:

Dates count from the first planting day of the window above; a later planting moves them by as many days.

Weather in Indianapolis during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, July, averages 29.7 °C. Months that stay below 18 °C even by day on average: November (11.3 °C). Nights average below 18 °C in May, June and September–November (2.4–17.6 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
May	22.9	12.4	120	14	14:21
June	28.4	17.6	89	11	14:58
July	29.7	19.8	124	13	14:44
August	28.5	18.7	88	10	13:46
September	26.2	15.9	76	7	12:30
October	19.5	9.7	82	10	11:12
November	11.3	2.4	72	9	10:01

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

Around Indianapolis, Evansville is 11 days earlier and Fort Wayne 5 days later.

City	Distance	Date	Difference
Cincinnati	159 km	13 May – 31 July	3 days earlier
Dayton	168 km	16 May – 31 July	same day
Fort Wayne	169 km	21 May – 24 July	5 days later
Louisville	173 km	7 May – 2 August	9 days earlier
Frankfort	207 km	13 May – 25 July	3 days earlier
Evansville	233 km	5 May – 1 August	11 days earlier

Where to buy watermelon plants and seeds near Indianapolis

Buy plants ready to set out from 16 May to 28 July (from 25 April to 28 July for an unheated greenhouse); seed for raising your own is sown from 28 March to 30 June. Within 15 km of Indianapolis OpenStreetMap lists 9 garden centres, 1 farm-supply shop, 2 plant nurseries and 4 markets (collected 20 October 2026).

Heath Outdoor — garden centre
3 km
Madeline F. Elder Greenhouse — garden centre
7 km
CHS Inc — garden centre
6 km
Feed and Seed Garden Center — garden centre
15 km

Each window starts on the Greenly calendar date and ends on the last day that still leaves the crop’s days to harvest (from its card) before the average first autumn frost, plus six weeks of picking for crops harvested over weeks (tomatoes, peppers, aubergines, cucumbers, courgettes, pumpkins, watermelons, beans) — our rule; earlier in the window is safer.

Questions